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Re: Foundation on Expansive Clay

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Item 1.

Fossil power plants produce flyash as a byproduct. The
plants are eager to get rid of this product, which
means you can get it cheap. For the size of indicated
foundation, i.e. 7'X8'X3', loosen 2' depth of existing
soil below the bottom level of foundation. Mix 20% by
volume (1.25 cyd) of flyash thorougly with the
loosened soil, in place and proof roll for compaction.
Build your conventional foundation. Lime can be used
if it is comparatively less expensive than flyash.

Item 2

I did not quite understand the first alternative using
a sleeve. Are you planning to embed the sleeve in the
foundation? If so, how deep? What connection would you
have between the mast and the sleeve? If I were you, I
would go with the second alternative of base plates


--- Fountain Conner <fconner(--nospam--at)> wrote:
> I need to put some lightly-loaded foundations on
> clay "with the potential
> for expansion".
> These foundations will carry a bark blowline in a
> paper mill.
> If all were normal these foundations would be 7 feet
> long x 8 feet wide x 3
> feet thick.  They each would have a vertical pipe 20
> feet tall, carrying a
> horizontal blowline.  Maximum soil pressure (max
> load and wind) would be
> about 2000 psf.  Static maximum load is about 650
> psf.  The geotechnical
> report allows at least 2500 psf, plus 25 percent for
> short-term live load
> (like wind).
> Plain vanilla...  Until I factor in the potentially
> expansive soil.  
> My thinking is to turn down the outside edge of the
> footing an additional 6
> inches.  If this clay is expansive, it shouldn't be
> given to capillary
> action, and will provide a seal, preventing the soil
> beneath the foundation
> from seeing the varying moisture content.
> What do you think?
> Item 2:
> I had intended to place each "mast" in a sleeve,
> plumb it and grout it
> into position -- cheap, but effective.  I *can* put
> a mast on a large,
> thick
> baseplate, and perch it on nuts below the base
> plate, with double nuts
> above.  If I do this, I can allow enough room below
> the lower nuts to
> adjust each mast plumb if there is some movement. 
> I'm hoping you guys can
> convince me that this step is overkill.
> Ideas?
> Thanx,
> Fountain E. Conner, P.E.
> Gulf Breeze, Fl. 32561
>    Phone 850-932-5547
>    Fax      850-934-1916
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